Background: Oral anticoagulation is used extensively for prevention of thromboembolic events. Whether acupuncture is safe for patients taking anticoagulants is not clear. Objective: To describe a patient with a history of ischemic stroke and paroxysmal nonvalvular atrial fibrillation who was in stroke rehabilitation including acupuncture. Design, Setting, and Patient The patient developed sudden calf hematoma when optimal therapeutic intensity of international normalized ratio (INR) was achieved. Results: This patient was treated conservatively, without symptoms of compartment syndrome, and calf hematomas were resolved in 3 months. Conclusions: With increased acceptance of acupuncture worldwide and enforcement of clinical guidelines for prevention of thromboembolism, acupuncture-induced hematoma will be an emerging clinical entity. To minimize hemorrhagic complications, caution should be exercised when patients receiving oral anticoagulation request acupuncture treatment.